There has been an increase in the need for selective reinforcement of automotive structures in order to meet various government test standards. To that end, structural foams and carriers have been developed for the purpose of reinforcing specific locations in vehicles. The primary focus of these reinforcements is to add strength or stiffness to a structure.
As will be appreciated by those skilled in the art, the three factors of greatest general importance in the evaluation of reinforcement effectiveness are stiffness, weight, and cost. With most prior art techniques, increasing stiffness results in a corresponding penalty of weight increase and/or cost increase. For example, while using thicker gages of metal increases strength, it results in an unwanted increase in weight. Similarly, the use of exotic high-strength alloys is effective to increase strength, but this adds considerably to the cost of the vehicle. Finally, it will be recognized that the cost of resins is also a concern and thus structural foams must be used sparingly.
Another concern in the use of structural foams is the problem associated with fully curing material that is very thick. That is, in some prior art applications the materials required to satisfactorily reinforce are so thick that it is difficult to achieve full cure. Therefore, it will be recognized that techniques for reinforcing hollow structures which do not cause a substantial weight and cost or curing problems have the potential to provide significant advantages.
It is therefore an object of the present invention to provide a structural reinforcement which utilizes structural foam in a manner which conserves resin.
It is a further object of the invention to provide such a reinforcement which can be fully cured in a short time.
It is still a further object to provide a low-cost, light-weight structural reinforcement which provides significant strength and stiffness to the reinforced region.
It is still a further object to provide a structural reinforcement which can be transported easily to the site of installation.